Unsuccessful with breeding zebra danios

Hi all,

I'm not sure what I'm doing wrong, but I can't get my zebra danios to spawn. I've done quite a bit of reading, and I feel like I'm doing pretty much everything right, but still no eggs. At the end of the post a list of all the things that (I think) I'm doing right. But I'm mostly curious about the behavior of my fish when I put them in their breeding containers; so first about that:

I have a 55 gallon tank with only 10 zebra danios. Besides 5 tiny phoenix rasboras those are the only fish in the tank. It's a heavily planted "aquascape" and water parameters are always perfect. The danios seem to be pretty happy in there! I always notice though that they behave quite different from danios I see in youtube videos or in the fish store. My danios seem to be much more chill and seem to mostly be exploring the tank, rather than schooling chaotically (like in all videos I can find with smaller tanks and more fish). But then, whenever put them in any other kind of container they freak the **** out. They either continuously swim against the wall/net of the container in a really frantic way, trying to find some sort of way out, or they just don't move at all for hours at a time. They just seem like they really don't like it and are extremely scared/freaking out. Is that normal?? In a way I'm actually really not surprised they're not mating being so angsty and all. So here's my theory: Maybe my large, understocked tank is a too nice of an environment and putting them in a small breeding tank is too much of environmental change for them to breed and not freak out. Could that be a thing?

So here the things I do when I try to bread them:
-I tried all kinds of containers. Tried a 5 gallon plastic tub with marbles. Had them in those clear plastic boxes (with false bottom with slits) with suction cups that you hang into the actual tank. Had those in different sizes and both had them in the 55 gallon main tank as well as in a separate 10 gallon tank so that the fish are more isolated from the rest. (Pretty sure the problem never is that the fish eat the eggs but rather that they don't spawn eggs in the first place
-I also tried having those containers slanted (which is supposed to increase spawning by simulating river banks)
-I definitely can distinguish males from females
-I separate the female for two days beforehand. Then put the male in with the female the night before and have them be together until the next day.
-I usually just pair only one female and one male. Is that bad? I'd like to know who the parents were haha.
-The only thing I'm not doing perfectly yet is that I'm not feeding live food. But the fish seem to have a really healthy size and the females definitely are really round and full of eggs most of the time. I did just buy some daphnia though and will try live food now. But could that really be the reason?

 

Have you tried messing with the temperature? When you place the pair in another container for spawning is it brightly lit? Live goods are certainly good to get some species to spawn but not necessary for zebra danios IMO.

Dropping the temp via a water change with slightly cooler water in the mornings can trigger spawning. They should not be in a brightly lit aquarium if it is basically bare bottom, a medium/dark substrate and some live plants may make them feel more comfortable. When I spawned mine I simply put a trio (2 males 1 female) in a 10gal with black gravel. They spawned over the course of 2 days then I removed them and waited to see tiny eyelash sized fry clinging to the glass. No special food, no live plants and just ambient room lighting.

Normally all that is needed (provided the females are gravid) is a temp drop of a few degrees and if they are comfortable they will spawn.

 

Hiya
Definately try the live food . Condition them for longer before you put them back together. Try a week , or two at a push. Fatten them up and let them rest, think of it like a spa break for us ! A few degrees cooler water changes usually works though.

If it’s stressing your fish to keep moving them then I just wouldn’t. They are common and cheap enough fish to not be worth the stress to the fish . If it’s heavily ‘aqua scaped’ then should be enough cover for the eggs to be safe? A picture of the tank would help ..

Pretty sure it’ll be mentioned that these fish are inbred and mass produced , meaning poor blood lines , sterile fish etc. did you want them to breed for your own stock / sale or just to experience it ?

 

I don't think live foods are necessary, but frozen or live, it couldn't hurt either, but there should be a period of "lean" when you don't want eggs, and then a period of excess when you do want eggs and spawning. there should be a water quality difference, this can help trigger spawning,
Rainy season is a trigger for a lot of fish, it rains, the water quality gets better for them, bugs and stuff get washed in and food is everywhere, the water temp drop a bit, it's all signals of a period of abundance to the fish, and this should trigger the females to actually spawn.
in the wild they live for like a year, in an aquarium, it's like 2-5 years. but in the wild, when the triggers are right, they are dropping eggs all the time, all the females at once, and trying to get reproduction done as much as possible before they die.

if your females aren't getting egg heavy, your method is off, maybe it's not heavier feedings, maybe it's not enough water change at once as a trigger, maybe it's the lighting timing which should be with sunrise and sunset, they spawn early morning, and it can throw off what they need to do if it's not consistent. or the ambient light changes before the tank or the tank comes on hours later. or the room the tank is in is never dark like night would be.

maybe you don't have a "lean time" so there is no significant difference to the fish for when abundance time is and its a good time to spawn.

there should be a visual difference between egg heavy and a female that isn't, if they are always looking egg heavy, it's likely it's just a fat fish and not eggs at all,,,,or she's holding really old eggs for a long time.

I wouldn't worry about a breederbox and saving eggs at first, I'd just be focused on the triggers to get the females to drop eggs for starters. You'd want them empty and making fresh ones for spawns to keep anyways, old eggs aren't very productive after about 4 days of holding them.

They should not be holding though, done right, they should be dropping eggs like every 10 days or so when the sun starts coming up and they think it's rainy season and there's plenty of food for the fry to eat around.

You have a 55g, I don't think you need to really separate the males from the females. there's plenty of room for them to have their separation I think.
I think it's likely a trigger isn't happening. maybe the sunrise trigger, maybe ambient light where the tank is kept is a problem and the fish don't know when sunrise really is so the females aren't dropping. as far as water changing, they should have dropped eggs by random chance if that was the issue your quality is good and I don't think the temperature thing is all that important if they are making eggs. they just aren't dropping them.

 

Wow thank you for all the replies! Sounds like very good advice that I'll definitely try to follow! Also, lots of things for me to answer...

Have you tried messing with the temperature? [...] Dropping the temp via a water change with slightly cooler water in the mornings can trigger spawning.

I'll try that! I just have all my fishtanks at room temperature (no heating), i.e. 22 C (72 F). I guess fresh cold tap-water would be colder, so I'll try that for the breeding tank. Could it be beneficial for breeding to raise the temperature of my main tank, i.e. get heating for my fish tank? I know my temperature is more towards the lower end of what danios like.

When you place the pair in another container for spawning is it brightly lit? [...] and some live plants

Nope, the tank I've been using for breeding actually doesn't have any artificial light. It's relatively close to a window however. And I do have live plants in the tank!

Condition them for longer before you put them back together. Try a week , or two at a push.

I'll definitely try that! Starting with a week today. Is it important for both males and females or is it actually only a thing for the females? Also, I was thinking it might help them not freak out so much if I put several females and (separately) several males together. Then when I put male and female together I could still pair only one and one.

I do also agree with what SparkyJones said though... my tank is pretty big and I never feel like the females are being chased around too much or anything. Typically the fish don't interact too much with each other and are all doing their own thing.

If it’s stressing your fish to keep moving them then I just wouldn’t. They are common and cheap enough fish to not be worth the stress to the fish. [...] Pretty sure it’ll be mentioned that these fish are inbred and mass produced , meaning poor blood lines , sterile fish etc. did you want them to breed for your own stock / sale or just to experience it ?

Nope, I'm definitely not doing this for financial reasons haha. I can't imagine that ever being worth it on my scale. Definitely for my own experience and as a fun experiment! For example, some of my fish happen have pretty unique traits and I think it would be fun to see what their offsprings would look like.

If it’s heavily ‘aqua scaped’ then should be enough cover for the eggs to be safe? A picture of the tank would help ..

Are you sure? That doesn't really make sense to me! I feel like even if the eggs survive, there's no way the fry will survive for more than a couple of days without eventually being eaten. As a matter of fact, I did see some fry at some point in the tank! But really not for very long. I'll take a picture of the tank next time I get a chance!


SparkyJones: Thanks for all the advice! Everything you say actually makes a lot of sense and agrees with what I'm suspecting. Everything seems to be right, except for the trigger to dop eggs. So maybe I'll just have to be better at simulating that environmental change with abundance of food and colder temperature.

there should be a visual difference between egg heavy and a female that isn't, if they are always looking egg heavy, it's likely it's just a fat fish and not eggs at all,,,,or she's holding really old eggs for a long time.

I definitely think I can distinguish between eggs and just a chubby fish. But the females are usually egg heavy for long stretches at a time. So I they're really just not dropping them very often.

maybe it's the lighting timing which should be with sunrise and sunset, they spawn early morning, and it can throw off what they need to do if it's not consistent. or the ambient light changes before the tank or the tank comes on hours later. or the room the tank is in is never dark like night would be.

I have been worried about the lighting. For one because my breeding tank is close to a window, so maybe the street light even is too bright? And the other thing is I often only go to bed at around 1am and then the sun goes up at around 6am. Is 5 hours of darkness enough time?